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It’s enchanting to consider that classical music might help plants grow better, like something out of a fairy tale. A simple Google search shows that a lot of people are interested in it, from the throngs at Yahoo Answers to marijuana growers looking for an edge. Mythbusters tested it, with mixed results. Academic researchers have explored the effects of tones on plant growth, finding frequency-specific gene regulation and growth responses. But it remains unclear what evolutionary benefit sensitivity to sound could provide, and a solid understanding of what is sometimes called ‘plant bioacoustics’ eludes researchers.

In a widely-reported study released last year, two researchers over at the University of Missouri, Columbia tested the effects on plant defenses of the vibrations caused by a caterpillar chewing on a leaf. Although much of the reporting fell prey to the temptation to claim the plants “heard” the chewing and responded, the real answer is both more complicated and more interesting. I had the opportunity to attend a talk Drs. Appel and Cocroft gave at Washington University a few months ago where I learned more than I could have extracted from their paper, published in Oecologia, alone.

Sound waves are longitudinal. Insect vibrations are transverse

Dr. Cocroft studies insect communication, especially the ability of insects to find mates and prey by sensing the vibrations of other insects on a plant. Like sound, the information is encoded in vibrational waves passing through a substance. Instead of a pressure wave like sound that varies in the same direction of travel—a longitudinal wave—insect vibrations on plants are transverse waves, moving up and down like a wave on the ocean (see figure).

We could never hear these kinds of waves ourselves, but their frequency can be directly translated to sounds we can hear. Cocroft played a number of humming soundscapes recorded with a laser on a wild prairie—the result of hundreds or thousands of insects communicating silently on stalks of grass. A plant, Cocroft noted, is a great conductor for these vibrations, flexible yet strong. His field studies how insects benefit from communicating this way, but he joined forces with Appel to ask: Do plants respond to the vibrations of insect herbivores in an adaptive way?

One major defense that plants have against pests is producing noxious compounds to deter feeding. Appel and Cocroft hypothesized that Arabidopsis plants would produce more defense compounds if they were exposed to the vibrations of herbivorous insects before actually being attacked. This effect is called priming, and could help defend against a second wave of insect damage.

To test this, the researchers first used lasers to record the vibrations of caterpillars allowed to eat the leaves of Arabidopsis plants. To play the vibrations back to undamaged plants, Cocroft attached leaves to tiny pistons driven, essentially, by speakers, ones that could replicate the vibrations of an insect chewing. Then caterpillars were allowed to feed on either the leaf that was vibrated or another, untouched leaf.

Both vibrated and distant leaves responded more vigorously to caterpillar attack than leaves on untouched plants. The plants that were primed by recorded caterpillar vibrations produced more glucosinolates, or mustard oils, than those of unvibrated plants. This is evidence of an adaptive response to insect vibrations, but leaves open the possibility that any vibration encouraged plant defenses.

To see if the effect really was specific to the herbivorous caterpillars, Appel and Cocroft played back vibrations of harmless insects, wind, or caterpillars on different plants and again measured defense compounds—this time anthocyanins, responsible for the deep reds and purples of many plants. Only caterpillar vibrations could prime plants to increase their defense response to herbivory; wind and the neutral insects had no effect.

One important caveat: although the researchers looked for an effect of vibrations alone, they found none. Only vibrations plus actual insect feeding induced higher defenses; the plants were primed for future attack, but vibrations alone made no difference. Of course, a real insect is more than just its vibrations. Herbivore attack is a physical, chemical, and auditory assault, and plants likely respond to each stimulus in different ways.

But how are plants able to sense the vibrations of caterpillars, and even differentiate them from similar sounds in nature? It’s entirely unknown. A very good candidate is a diverse group of proteins bound together by their responsiveness to physical forces—mechanoreceptors. These proteins can signal within a cell in response to vibration or touch and are potentially behind the priming effect that Appel and Cocroft observed.

In fact, to test this, the Haswell lab is working with Appel and Cocroft to see if our favorite mechanosensitive ion channels are part of the vibrational-response pathway. I got to see Liz’s face pop up in the corner at the end of their presentation over on the medical campus as they told us that work was underway. We’ll just have to wait to find out.

Dating — online or off — is frustrating and bewildering, a long and tearful journey to a great partner. While technology has absolutely transformed how we find potential dates, the most significant change is cultural. Instead of settling down with someone “good enough” we ask so much from our partners now that it’s only natural the search for them is arduous.

Our conversations about civic matters—economic policies, schooling systems, religion, science, and social institutions—are severely lacking in nuance and reasoned debate. Instead, what flourishes are simplistic arguments and ad hominem attacks. This trend is strengthened by a media environment where we can easily consume pieces tailored to our point of view, avoiding challenge and change.

On Being is a weekly public radio show hosted by Krista Tippett ostensibly about religion and spirituality, but now the host of a broader series of discussions called the Civil Conversations Project. I used to turn off On Being when it came on my radio Sunday afternoons, put off by the wispy quality, assuming it was a liberal echo chamber of feel-good, empty spirituality.

But as I would listen in snippets, or accidentally turn it on in the car, I found it to be a series of careful, respectful dialogues about difficult subjects, with religion, of course, among the trickiest.

So it did not altogether surprise me to find myself enchanted by arecent episode on gay marriage, which really became a window into how to have civil debates. An interview of David Blankenhorn and Jonathon Rauch—originally on opposite sides of the gay marriage debate, and now friends in agreement on many issues—the discussion covered David’s changed mind on gay marriage, but much more interestingly their process of what they called “achieving disagreement.”

For this post I really want to excerpt some longer segments that, I think, speak for themselves. I encourage listening to the full episode. To have two people agree about how to disagree, that are intellectually honest in their point of view and empathetic enough to consider the other side is tragically rare these days and models a better way to converse. I think we can learn from them how to continue to passionately disagree while remaining not just polite, but truly civil.